The airlines are demanding changes to the government's quarantine rules
The UK government had imposed a ruling from 8 June that any traveller will have to self-isolate for two weeks due to the coronavirus outbreak situation and the decision has irked airlines, who are arguing that it is not necessary to do so.
That is resulting in the legal action being taken here, although I'm not sure how this will actually play out to be honest.
But the airlines are demanding the government to adopt back its previous quarantine ruling back in March, whereby only travellers from "high risk" countries are needed to adhere to the two-week self-quarantine period.
Not the least bit surprising as a two-week quarantine would basically defeat any purpose of travel to the UK for business/leisure at this stage. And that's bad business for the travel sector and for airlines in general.